Add shader translator support for OVR_multiview

include/GLSLANG/ShaderLang.h

@@ -25,7 +25,7 @@
 
 // Version number for shader translation API.
 // It is incremented every time the API changes.
-#define ANGLE_SH_VERSION 169
+#define ANGLE_SH_VERSION 170
 
 enum ShShaderSpec
 {
@@ -214,6 +214,10 @@ const ShCompileOptions SH_REWRITE_FLOAT_UNARY_MINUS_OPERATOR = UINT64_C(1) << 29
 // It works by using an expression to emulate this function.
 const ShCompileOptions SH_EMULATE_ATAN2_FLOAT_FUNCTION = UINT64_C(1) << 30;
 
+// Set to 1 to translate gl_ViewID_OVR to an uniform so that the extension can be emulated.
+// "uniform highp uint webgl_angle_ViewID_OVR".
+const ShCompileOptions SH_TRANSLATE_VIEWID_OVR_TO_UNIFORM = UINT64_C(1) << 31;
+
 // Defines alternate strategies for implementing array index clamping.
 enum ShArrayIndexClampingStrategy
 {
@@ -259,6 +263,7 @@ struct ShBuiltInResources
     int EXT_shader_framebuffer_fetch;
     int NV_shader_framebuffer_fetch;
     int ARM_shader_framebuffer_fetch;
+    int OVR_multiview;
 
     // Set to 1 to enable replacing GL_EXT_draw_buffers #extension directives
     // with GL_NV_draw_buffers in ESSL output. This flag can be used to emulate
@@ -285,6 +290,9 @@ struct ShBuiltInResources
     // GLES SL version 100 gl_MaxDualSourceDrawBuffersEXT value for EXT_blend_func_extended.
     int MaxDualSourceDrawBuffers;
 
+    // Value of GL_MAX_VIEWS_OVR.
+    int MaxViewsOVR;
+
     // Name Hashing.
     // Set a 64 bit hash function to enable user-defined name hashing.
     // Default is NULL.
@@ -488,6 +496,7 @@ const std::vector<sh::Attribute> *ShGetAttributes(const ShHandle handle);
 const std::vector<sh::OutputVariable> *ShGetOutputVariables(const ShHandle handle);
 const std::vector<sh::InterfaceBlock> *ShGetInterfaceBlocks(const ShHandle handle);
 sh::WorkGroupSize ShGetComputeShaderLocalGroupSize(const ShHandle handle);
+int ShGetVertexShaderNumViews(const ShHandle handle);
 
 // Returns true if the passed in variables pack in maxVectors following
 // the packing rules from the GLSL 1.017 spec, Appendix A, section 7.
@@ -629,6 +638,7 @@ const std::vector<sh::Attribute> *GetAttributes(const ShHandle handle);
 const std::vector<sh::OutputVariable> *GetOutputVariables(const ShHandle handle);
 const std::vector<sh::InterfaceBlock> *GetInterfaceBlocks(const ShHandle handle);
 sh::WorkGroupSize GetComputeShaderLocalGroupSize(const ShHandle handle);
+int GetVertexShaderNumViews(const ShHandle handle);
 
 // Returns true if the passed in variables pack in maxVectors followingthe packing rules from the
 // GLSL 1.017 spec, Appendix A, section 7.

samples/shader_translator/shader_translator.cpp

@@ -205,6 +205,10 @@ int main(int argc, char *argv[])
                       case 'f': resources.EXT_shader_framebuffer_fetch = 1; break;
                       case 'n': resources.NV_shader_framebuffer_fetch = 1; break;
                       case 'a': resources.ARM_shader_framebuffer_fetch = 1; break;
+                      case 'm':
+                          resources.OVR_multiview = 1;
+                          compileOptions |= SH_TRANSLATE_VIEWID_OVR_TO_UNIFORM;
+                          break;
                       default: failCode = EFailUsage;
                     }
                     // clang-format on
@@ -339,7 +343,8 @@ void usage()
         "       -x=l     : enable EXT_shader_texture_lod\n"
         "       -x=f     : enable EXT_shader_framebuffer_fetch\n"
         "       -x=n     : enable NV_shader_framebuffer_fetch\n"
-        "       -x=a     : enable ARM_shader_framebuffer_fetch\n");
+        "       -x=a     : enable ARM_shader_framebuffer_fetch\n"
+        "       -x=m     : enable OVR_multiview\n");
     // clang-format on
 }
 

src/compiler.gypi

@@ -52,6 +52,8 @@
             'compiler/translator/ExpandIntegerPowExpressions.cpp',
             'compiler/translator/ExpandIntegerPowExpressions.h',
             'compiler/translator/ExtensionBehavior.h',
+            'compiler/translator/FindSymbolNode.cpp',
+            'compiler/translator/FindSymbolNode.h',
             'compiler/translator/FlagStd140Structs.cpp',
             'compiler/translator/FlagStd140Structs.h',
             'compiler/translator/HashNames.h',
@@ -120,6 +122,8 @@
             'compiler/translator/ValidateLimitations.h',
             'compiler/translator/ValidateMaxParameters.h',
             'compiler/translator/ValidateMaxParameters.cpp',
+            'compiler/translator/ValidateMultiviewWebGL.cpp',
+            'compiler/translator/ValidateMultiviewWebGL.h',
             'compiler/translator/ValidateOutputs.cpp',
             'compiler/translator/ValidateOutputs.h',
             'compiler/translator/ValidateSwitch.cpp',

src/compiler/translator/BaseTypes.h

@@ -488,6 +488,8 @@ enum TQualifier
     EvqSecondaryFragColorEXT,  // EXT_blend_func_extended
     EvqSecondaryFragDataEXT,   // EXT_blend_func_extended
 
+    EvqViewIDOVR,  // OVR_multiview
+
     // built-ins written by the shader_framebuffer_fetch extension(s)
     EvqLastFragColor,
     EvqLastFragData,
@@ -575,6 +577,9 @@ struct TLayoutQualifier
     // Image format layout qualifier
     TLayoutImageInternalFormat imageInternalFormat;
 
+    // OVR_multiview num_views.
+    int numViews;
+
     static TLayoutQualifier create()
     {
         TLayoutQualifier layoutQualifier;
@@ -585,6 +590,7 @@ struct TLayoutQualifier
         layoutQualifier.blockStorage       = EbsUnspecified;
 
         layoutQualifier.localSize.fill(-1);
+        layoutQualifier.numViews = -1;
 
         layoutQualifier.imageInternalFormat = EiifUnspecified;
         return layoutQualifier;
@@ -592,7 +598,7 @@ struct TLayoutQualifier
 
     bool isEmpty() const
     {
-        return location == -1 && matrixPacking == EmpUnspecified &&
+        return location == -1 && numViews == -1 && matrixPacking == EmpUnspecified &&
                blockStorage == EbsUnspecified && !localSize.isAnyValueSet() &&
                imageInternalFormat == EiifUnspecified;
     }
@@ -600,12 +606,16 @@ struct TLayoutQualifier
     bool isCombinationValid() const
     {
         bool workSizeSpecified = localSize.isAnyValueSet();
+        bool numViewsSet       = (numViews != -1);
         bool otherLayoutQualifiersSpecified =
             (location != -1 || matrixPacking != EmpUnspecified || blockStorage != EbsUnspecified ||
              imageInternalFormat != EiifUnspecified);
 
-        // we can have either the work group size specified, or the other layout qualifiers
-        return !(workSizeSpecified && otherLayoutQualifiersSpecified);
+        // we can have either the work group size specified, or number of views, or the other layout
+        // qualifiers.
+        return (workSizeSpecified ? 1 : 0) + (numViewsSet ? 1 : 0) +
+                   (otherLayoutQualifiersSpecified ? 1 : 0) <=
+               1;
     }
 
     bool isLocalSizeEqual(const sh::WorkGroupSize &localSizeIn) const
@@ -697,6 +707,7 @@ inline const char *getQualifierString(TQualifier q)
     case EvqFragDepth:              return "FragDepth";
     case EvqSecondaryFragColorEXT:  return "SecondaryFragColorEXT";
     case EvqSecondaryFragDataEXT:   return "SecondaryFragDataEXT";
+    case EvqViewIDOVR:              return "ViewIDOVR";
     case EvqLastFragColor:          return "LastFragColor";
     case EvqLastFragData:           return "LastFragData";
     case EvqSmoothOut:              return "smooth out";

src/compiler/translator/Compiler.cpp

@@ -30,6 +30,7 @@
 #include "compiler/translator/UseInterfaceBlockFields.h"
 #include "compiler/translator/ValidateLimitations.h"
 #include "compiler/translator/ValidateMaxParameters.h"
+#include "compiler/translator/ValidateMultiviewWebGL.h"
 #include "compiler/translator/ValidateOutputs.h"
 #include "compiler/translator/VariablePacker.h"
 #include "third_party/compiler/ArrayBoundsClamper.h"
@@ -320,11 +321,22 @@ TIntermBlock *TCompiler::compileTreeImpl(const char *const shaderStrings[],
         mComputeShaderLocalSizeDeclared = parseContext.isComputeShaderLocalSizeDeclared();
         mComputeShaderLocalSize         = parseContext.getComputeShaderLocalSize();
 
+        mNumViews = parseContext.getNumViews();
+
         root = parseContext.getTreeRoot();
 
         // Highp might have been auto-enabled based on shader version
         fragmentPrecisionHigh = parseContext.getFragmentPrecisionHigh();
 
+        if (success && (IsWebGLBasedSpec(shaderSpec) &&
+                        IsExtensionEnabled(extensionBehavior, "GL_OVR_multiview") &&
+                        IsExtensionEnabled(extensionBehavior, "GL_OVR_multiview2")))
+        {
+            // Can't enable both extensions at the same time.
+            mDiagnostics.globalError("Can't enable both OVR_multiview and OVR_multiview2");
+            success = false;
+        }
+
         // Disallow expressions deemed too complex.
         if (success && (compileOptions & SH_LIMIT_EXPRESSION_COMPLEXITY))
             success = limitExpressionComplexity(root);
@@ -358,6 +370,11 @@ TIntermBlock *TCompiler::compileTreeImpl(const char *const shaderStrings[],
         if (success && shouldRunLoopAndIndexingValidation(compileOptions))
             success = validateLimitations(root);
 
+        bool multiview2 = IsExtensionEnabled(extensionBehavior, "GL_OVR_multiview2");
+        if (success && compileResources.OVR_multiview && IsWebGLBasedSpec(shaderSpec) &&
+            (IsExtensionEnabled(extensionBehavior, "GL_OVR_multiview") || multiview2))
+            success = ValidateMultiviewWebGL(root, shaderType, multiview2, &mDiagnostics);
+
         // Fail compilation if precision emulation not supported.
         if (success && getResources().WEBGL_debug_shader_precision &&
             getPragma().debugShaderPrecision)
@@ -650,6 +667,8 @@ void TCompiler::clearResults()
     interfaceBlocks.clear();
     variablesCollected = false;
 
+    mNumViews = -1;
+
     builtInFunctionEmulator.Cleanup();
 
     nameMap.clear();

src/compiler/translator/Compiler.h

@@ -101,7 +101,8 @@ class TCompiler : public TShHandleBase
     TInfoSink &getInfoSink() { return infoSink; }
 
     bool isComputeShaderLocalSizeDeclared() const { return mComputeShaderLocalSizeDeclared; }
-    const sh::WorkGroupSize &getComputeShaderLocalSize() { return mComputeShaderLocalSize; }
+    const sh::WorkGroupSize &getComputeShaderLocalSize() const { return mComputeShaderLocalSize; }
+    int getNumViews() const { return mNumViews; }
 
     // Clears the results from the previous compilation.
     void clearResults();
@@ -247,6 +248,9 @@ class TCompiler : public TShHandleBase
     bool mComputeShaderLocalSizeDeclared;
     sh::WorkGroupSize mComputeShaderLocalSize;
 
+    // GL_OVR_multiview num_views.
+    int mNumViews;
+
     // name hashing.
     ShHashFunction64 hashFunction;
     NameMap nameMap;

src/compiler/translator/FindSymbolNode.cpp

+//
+// Copyright (c) 2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// FindSymbol.cpp:
+//     Utility for finding a symbol node inside an AST tree.
+
+#include "compiler/translator/FindSymbolNode.h"
+
+#include "compiler/translator/IntermNode.h"
+
+namespace sh
+{
+
+namespace
+{
+
+class SymbolFinder : public TIntermTraverser
+{
+  public:
+    SymbolFinder(const TString &symbolName, TBasicType basicType)
+        : TIntermTraverser(true, false, false),
+          mSymbolName(symbolName),
+          mNodeFound(nullptr),
+          mBasicType(basicType)
+    {
+    }
+
+    void visitSymbol(TIntermSymbol *node)
+    {
+        if (node->getBasicType() == mBasicType && node->getSymbol() == mSymbolName)
+        {
+            mNodeFound = node;
+        }
+    }
+
+    bool isFound() const { return mNodeFound != nullptr; }
+    const TIntermSymbol *getNode() const { return mNodeFound; }
+
+  private:
+    TString mSymbolName;
+    TIntermSymbol *mNodeFound;
+    TBasicType mBasicType;
+};
+
+}  // anonymous namespace
+
+const TIntermSymbol *FindSymbolNode(TIntermNode *root,
+                                    const TString &symbolName,
+                                    TBasicType basicType)
+{
+    SymbolFinder finder(symbolName, basicType);
+    root->traverse(&finder);
+    return finder.getNode();
+}
+
+}  // namespace sh

src/compiler/translator/FindSymbolNode.h

+//
+// Copyright (c) 2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// FindSymbolNode.h:
+//     Utility for finding a symbol node inside an AST tree.
+
+#ifndef COMPILER_TRANSLATOR_FIND_SYMBOL_H_
+#define COMPILER_TRANSLATOR_FIND_SYMBOL_H_
+
+#include "compiler/translator/BaseTypes.h"
+#include "compiler/translator/Common.h"
+
+namespace sh
+{
+
+class TIntermNode;
+class TIntermSymbol;
+
+const TIntermSymbol *FindSymbolNode(TIntermNode *root,
+                                    const TString &symbolName,
+                                    TBasicType basicType);
+
+}  // namespace sh
+
+#endif  // COMPILER_TRANSLATOR_FIND_SYMBOL_H_
\ No newline at end of file

src/compiler/translator/Initialize.cpp

@@ -706,6 +706,14 @@ void IdentifyBuiltIns(sh::GLenum type,
     // Insert some special built-in variables that are not in
     // the built-in header files.
     //
+
+    if (resources.OVR_multiview && type != GL_COMPUTE_SHADER)
+    {
+        symbolTable.insert(COMMON_BUILTINS, "GL_OVR_multiview",
+                           new TVariable(NewPoolTString("gl_ViewID_OVR"),
+                                         TType(EbtUInt, EbpHigh, EvqViewIDOVR, 1)));
+    }
+
     switch (type)
     {
         case GL_FRAGMENT_SHADER:
@@ -858,6 +866,11 @@ void InitExtensionBehavior(const ShBuiltInResources &resources, TExtensionBehavi
         extBehavior["GL_NV_shader_framebuffer_fetch"] = EBhUndefined;
     if (resources.ARM_shader_framebuffer_fetch)
         extBehavior["GL_ARM_shader_framebuffer_fetch"] = EBhUndefined;
+    if (resources.OVR_multiview)
+    {
+        extBehavior["GL_OVR_multiview"]  = EBhUndefined;
+        extBehavior["GL_OVR_multiview2"] = EBhUndefined;
+    }
 }
 
 void ResetExtensionBehavior(TExtensionBehavior &extBehavior)

src/compiler/translator/IntermNode.cpp

@@ -838,6 +838,11 @@ bool TIntermSwizzle::hasDuplicateOffsets() const
     return false;
 }
 
+bool TIntermSwizzle::offsetsMatch(int offset) const
+{
+    return mSwizzleOffsets.size() == 1 && mSwizzleOffsets[0] == offset;
+}
+
 void TIntermSwizzle::writeOffsetsAsXYZW(TInfoSinkBase *out) const
 {
     for (const int offset : mSwizzleOffsets)

src/compiler/translator/IntermNode.h

@@ -430,6 +430,7 @@ class TIntermSwizzle : public TIntermTyped
     void writeOffsetsAsXYZW(TInfoSinkBase *out) const;
 
     bool hasDuplicateOffsets() const;
+    bool offsetsMatch(int offset) const;
 
     TIntermTyped *fold();
 

src/compiler/translator/OutputGLSLBase.cpp

@@ -1279,7 +1279,16 @@ TString TOutputGLSLBase::hashName(const TName &name)
 TString TOutputGLSLBase::hashVariableName(const TName &name)
 {
     if (mSymbolTable.findBuiltIn(name.getString(), mShaderVersion) != NULL)
+    {
+        if (mCompileOptions & SH_TRANSLATE_VIEWID_OVR_TO_UNIFORM &&
+            name.getString() == "gl_ViewID_OVR")
+        {
+            TName uniformName(TString("ViewId_OVR"));
+            uniformName.setInternal(true);
+            return hashName(uniformName);
+        }
         return name.getString();
+    }
     return hashName(name);
 }
 

src/compiler/translator/OutputGLSLBase.h

@@ -30,6 +30,11 @@ class TOutputGLSLBase : public TIntermTraverser
 
     ShShaderOutput getShaderOutput() const { return mOutput; }
 
+    // Return the original name if hash function pointer is NULL;
+    // otherwise return the hashed name. Has special handling for internal names, which are not
+    // hashed.
+    TString hashName(const TName &name);
+
   protected:
     TInfoSinkBase &objSink() { return mObjSink; }
     void writeFloat(TInfoSinkBase &out, float f);
@@ -62,9 +67,6 @@ class TOutputGLSLBase : public TIntermTraverser
 
     void visitCodeBlock(TIntermBlock *node);
 
-    // Return the original name if hash function pointer is NULL;
-    // otherwise return the hashed name.
-    TString hashName(const TName &name);
     // Same as hashName(), but without hashing built-in variables.
     TString hashVariableName(const TName &name);
     // Same as hashName(), but without hashing built-in functions and with unmangling.

src/compiler/translator/ParseContext.cpp

@@ -106,7 +106,10 @@ TParseContext::TParseContext(TSymbolTable &symt,
       mUsesSecondaryOutputs(false),
       mMinProgramTexelOffset(resources.MinProgramTexelOffset),
       mMaxProgramTexelOffset(resources.MaxProgramTexelOffset),
+      mMultiviewAvailable(resources.OVR_multiview == 1),
       mComputeShaderLocalSizeDeclared(false),
+      mNumViews(-1),
+      mMaxNumViews(resources.MaxViewsOVR),
       mDeclaringFunction(false)
 {
     mComputeShaderLocalSize.fill(-1);
@@ -1085,6 +1088,12 @@ bool TParseContext::checkCanUseExtension(const TSourceLoc &line, const TString &
     // In GLSL ES, an extension's default behavior is "disable".
     if (iter->second == EBhDisable || iter->second == EBhUndefined)
     {
+        // TODO(oetuaho@nvidia.com): This is slightly hacky. Might be better if symbols could be
+        // associated with more than one extension.
+        if (extension == "GL_OVR_multiview")
+        {
+            return checkCanUseExtension(line, "GL_OVR_multiview2");
+        }
         error(line, "extension is disabled", extension.c_str());
         return false;
     }
@@ -1481,6 +1490,14 @@ TIntermTyped *TParseContext::parseVariableIdentifier(const TSourceLoc &location,
 {
     const TVariable *variable = getNamedVariable(location, name, symbol);
 
+    if (variable->getType().getQualifier() == EvqViewIDOVR && IsWebGLBasedSpec(mShaderSpec) &&
+        mShaderType == GL_FRAGMENT_SHADER && !isExtensionEnabled("GL_OVR_multiview2"))
+    {
+        // WEBGL_multiview spec
+        error(location, "Need to enable OVR_multiview2 to use gl_ViewID_OVR in fragment shader",
+              "gl_ViewID_OVR");
+    }
+
     if (variable->getConstPointer())
     {
         const TConstantUnion *constArray = variable->getConstPointer();
@@ -2315,10 +2332,37 @@ void TParseContext::parseGlobalLayoutQualifier(const TTypeQualifierBuilder &type
 
         mComputeShaderLocalSizeDeclared = true;
     }
-    else
+    else if (mMultiviewAvailable &&
+             (isExtensionEnabled("GL_OVR_multiview") || isExtensionEnabled("GL_OVR_multiview2")) &&
+             typeQualifier.qualifier == EvqVertexIn)
     {
+        // This error is only specified in WebGL, but tightens unspecified behavior in the native
+        // specification.
+        if (mNumViews != -1 && layoutQualifier.numViews != mNumViews)
+        {
+            error(typeQualifier.line, "Number of views does not match the previous declaration",
+                  "layout");
+            return;
+        }
+
+        if (layoutQualifier.numViews == -1)
+        {
+            error(typeQualifier.line, "No num_views specified", "layout");
+            return;
+        }
+
+        if (layoutQualifier.numViews > mMaxNumViews)
+        {
+            error(typeQualifier.line, "num_views greater than the value of GL_MAX_VIEWS_OVR",
+                  "layout");
+            return;
+        }
 
-        if (!checkWorkGroupSizeIsNotSpecified(typeQualifier.line, typeQualifier.layoutQualifier))
+        mNumViews = layoutQualifier.numViews;
+    }
+    else
+    {
+        if (!checkWorkGroupSizeIsNotSpecified(typeQualifier.line, layoutQualifier))
         {
             return;
         }
@@ -2337,7 +2381,7 @@ void TParseContext::parseGlobalLayoutQualifier(const TTypeQualifierBuilder &type
             return;
         }
 
-        checkLocationIsNotSpecified(typeQualifier.line, typeQualifier.layoutQualifier);
+        checkLocationIsNotSpecified(typeQualifier.line, layoutQualifier);
 
         if (layoutQualifier.matrixPacking != EmpUnspecified)
         {
@@ -3348,6 +3392,20 @@ void TParseContext::parseLocalSize(const TString &qualifierType,
     (*localSize)[index] = intValue;
 }
 
+void TParseContext::parseNumViews(int intValue,
+                                  const TSourceLoc &intValueLine,
+                                  const std::string &intValueString,
+                                  int *numViews)
+{
+    // This error is only specified in WebGL, but tightens unspecified behavior in the native
+    // specification.
+    if (intValue < 1)
+    {
+        error(intValueLine, "out of range: num_views must be positive", intValueString.c_str());
+    }
+    *numViews = intValue;
+}
+
 TLayoutQualifier TParseContext::parseLayoutQualifier(const TString &qualifierType,
                                                      const TSourceLoc &qualifierTypeLine,
                                                      int intValue,
@@ -3386,6 +3444,12 @@ TLayoutQualifier TParseContext::parseLayoutQualifier(const TString &qualifierTyp
         parseLocalSize(qualifierType, qualifierTypeLine, intValue, intValueLine, intValueString, 2u,
                        &qualifier.localSize);
     }
+    else if (qualifierType == "num_views" && mMultiviewAvailable &&
+             (isExtensionEnabled("GL_OVR_multiview") || isExtensionEnabled("GL_OVR_multiview2")) &&
+             mShaderType == GL_VERTEX_SHADER)
+    {
+        parseNumViews(intValue, intValueLine, intValueString, &qualifier.numViews);
+    }
     else
     {
         error(qualifierTypeLine, "invalid layout qualifier", qualifierType.c_str());

src/compiler/translator/ParseContext.h

@@ -81,6 +81,8 @@ class TParseContext : angle::NonCopyable
     bool isComputeShaderLocalSizeDeclared() const { return mComputeShaderLocalSizeDeclared; }
     sh::WorkGroupSize getComputeShaderLocalSize() const;
 
+    int getNumViews() const { return mNumViews; }
+
     void enterFunctionDeclaration() { mDeclaringFunction = true; }
 
     void exitFunctionDeclaration() { mDeclaringFunction = false; }
@@ -294,6 +296,10 @@ class TParseContext : angle::NonCopyable
                         const std::string &intValueString,
                         size_t index,
                         sh::WorkGroupSize *localSize);
+    void parseNumViews(int intValue,
+                       const TSourceLoc &intValueLine,
+                       const std::string &intValueString,
+                       int *numViews);
     TLayoutQualifier parseLayoutQualifier(const TString &qualifierType,
                                           const TSourceLoc &qualifierTypeLine);
     TLayoutQualifier parseLayoutQualifier(const TString &qualifierType,
@@ -445,9 +451,14 @@ class TParseContext : angle::NonCopyable
     int mMinProgramTexelOffset;
     int mMaxProgramTexelOffset;
 
+    bool mMultiviewAvailable;
+
     // keep track of local group size declared in layout. It should be declared only once.
     bool mComputeShaderLocalSizeDeclared;
     sh::WorkGroupSize mComputeShaderLocalSize;
+    // keep track of number of views declared in layout.
+    int mNumViews;
+    int mMaxNumViews;
     // keeps track whether we are declaring / defining a function
     bool mDeclaringFunction;
 };

src/compiler/translator/QualifierTypes.cpp

@@ -584,6 +584,11 @@ TLayoutQualifier JoinLayoutQualifiers(TLayoutQualifier leftQualifier,
         }
     }
 
+    if (rightQualifier.numViews != -1)
+    {
+        joinedQualifier.numViews = rightQualifier.numViews;
+    }
+
     if (rightQualifier.imageInternalFormat != EiifUnspecified)
     {
         joinedQualifier.imageInternalFormat = rightQualifier.imageInternalFormat;

src/compiler/translator/ShaderLang.cpp

@@ -161,6 +161,7 @@ void ShInitBuiltInResources(ShBuiltInResources *resources)
     resources->EXT_shader_framebuffer_fetch    = 0;
     resources->NV_shader_framebuffer_fetch     = 0;
     resources->ARM_shader_framebuffer_fetch    = 0;
+    resources->OVR_multiview                   = 0;
 
     resources->NV_draw_buffers = 0;
 
@@ -176,6 +177,8 @@ void ShInitBuiltInResources(ShBuiltInResources *resources)
     // Extensions constants.
     resources->MaxDualSourceDrawBuffers = 0;
 
+    resources->MaxViewsOVR = 2;
+
     // Disable name hashing by default.
     resources->HashFunction = NULL;
 
@@ -371,6 +374,16 @@ WorkGroupSize ShGetComputeShaderLocalGroupSize(const ShHandle handle)
     return compiler->getComputeShaderLocalSize();
 }
 
+int ShGetVertexShaderNumViews(const ShHandle handle)
+{
+    ASSERT(handle);
+    TShHandleBase *base = static_cast<TShHandleBase *>(handle);
+    TCompiler *compiler = base->getAsCompiler();
+    ASSERT(compiler);
+
+    return compiler->getNumViews();
+}
+
 bool ShCheckVariablesWithinPackingLimits(int maxVectors,
                                          const std::vector<ShaderVariable> &variables)
 {
@@ -512,6 +525,11 @@ sh::WorkGroupSize GetComputeShaderLocalGroupSize(const ShHandle handle)
     return ShGetComputeShaderLocalGroupSize(handle);
 }
 
+int GetVertexShaderNumViews(const ShHandle handle)
+{
+    return ShGetVertexShaderNumViews(handle);
+}
+
 bool CheckVariablesWithinPackingLimits(int maxVectors,
                                        const std::vector<sh::ShaderVariable> &variables)
 {

src/compiler/translator/TranslatorESSL.cpp

@@ -40,7 +40,7 @@ void TranslatorESSL::translate(TIntermNode *root, ShCompileOptions compileOption
     }
 
     // Write built-in extension behaviors.
-    writeExtensionBehavior();
+    writeExtensionBehavior(compileOptions);
 
     // Write pragmas after extensions because some drivers consider pragmas
     // like non-preprocessor tokens.
@@ -94,6 +94,14 @@ void TranslatorESSL::translate(TIntermNode *root, ShCompileOptions compileOption
     TOutputESSL outputESSL(sink, getArrayIndexClampingStrategy(), getHashFunction(), getNameMap(),
                            getSymbolTable(), getShaderType(), shaderVer, precisionEmulation,
                            compileOptions);
+
+    if (compileOptions & SH_TRANSLATE_VIEWID_OVR_TO_UNIFORM)
+    {
+        TName uniformName(TString("ViewId_OVR"));
+        uniformName.setInternal(true);
+        sink << "highp uniform int " << outputESSL.hashName(uniformName) << ";\n";
+    }
+
     root->traverse(&outputESSL);
 }
 
@@ -103,7 +111,7 @@ bool TranslatorESSL::shouldFlattenPragmaStdglInvariantAll()
     return false;
 }
 
-void TranslatorESSL::writeExtensionBehavior()
+void TranslatorESSL::writeExtensionBehavior(ShCompileOptions compileOptions)
 {
     TInfoSinkBase &sink                   = getInfoSink().obj;
     const TExtensionBehavior &extBehavior = getExtensionBehavior();
@@ -123,6 +131,12 @@ void TranslatorESSL::writeExtensionBehavior()
                 sink << "#extension GL_NV_draw_buffers : " << getBehaviorString(iter->second)
                      << "\n";
             }
+            else if (compileOptions & SH_TRANSLATE_VIEWID_OVR_TO_UNIFORM &&
+                     (iter->first == "GL_OVR_multiview" || iter->first == "GL_OVR_multiview2"))
+            {
+                // No output
+                continue;
+            }
             else
             {
                 sink << "#extension " << iter->first << " : " << getBehaviorString(iter->second)

src/compiler/translator/TranslatorESSL.h

@@ -25,7 +25,7 @@ class TranslatorESSL : public TCompiler
     bool shouldFlattenPragmaStdglInvariantAll() override;
 
   private:
-    void writeExtensionBehavior();
+    void writeExtensionBehavior(ShCompileOptions compileOptions);
 };
 
 }  // namespace sh

src/compiler/translator/TranslatorGLSL.cpp

@@ -204,6 +204,14 @@ void TranslatorGLSL::translate(TIntermNode *root, ShCompileOptions compileOption
     TOutputGLSL outputGLSL(sink, getArrayIndexClampingStrategy(), getHashFunction(), getNameMap(),
                            getSymbolTable(), getShaderType(), getShaderVersion(), getOutputType(),
                            compileOptions);
+
+    if (compileOptions & SH_TRANSLATE_VIEWID_OVR_TO_UNIFORM)
+    {
+        TName uniformName(TString("ViewId_OVR"));
+        uniformName.setInternal(true);
+        sink << "uniform int " << outputGLSL.hashName(uniformName) << ";\n";
+    }
+
     root->traverse(&outputGLSL);
 }
 

src/compiler/translator/ValidateMultiviewWebGL.h

+//
+// Copyright (c) 2002-2016 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// ValidateMultiviewWebGL.h:
+//   Validate the AST according to rules in the WEBGL_multiview extension spec. Only covers those
+//   rules not already covered in ParseContext.
+//
+
+#ifndef COMPILER_TRANSLATOR_VALIDATEMULTIVIEWWEBGL_H_
+#define COMPILER_TRANSLATOR_VALIDATEMULTIVIEWWEBGL_H_
+
+#include "GLSLANG/ShaderVars.h"
+
+namespace sh
+{
+class TDiagnostics;
+class TIntermBlock;
+
+// Check for errors and output error messages with diagnostics.
+// Returns true if there are no errors.
+bool ValidateMultiviewWebGL(TIntermBlock *root,
+                            sh::GLenum shaderType,
+                            bool multiview2,
+                            TDiagnostics *diagnostics);
+
+}  // namespace sh
+
+#endif  // COMPILER_TRANSLATOR_VALIDATEMULTIVIEWWEBGL_H_

src/tests/angle_unittests.gypi

@@ -72,6 +72,7 @@
             '<(angle_path)/src/tests/compiler_tests/ShCompile_test.cpp',
             '<(angle_path)/src/tests/compiler_tests/TypeTracking_test.cpp',
             '<(angle_path)/src/tests/compiler_tests/VariablePacker_test.cpp',
+            '<(angle_path)/src/tests/compiler_tests/WEBGL_multiview_test.cpp',
             '<(angle_path)/src/tests/compiler_tests/WorkGroupSize_test.cpp',
             '<(angle_path)/src/tests/preprocessor_tests/char_test.cpp',
             '<(angle_path)/src/tests/preprocessor_tests/comment_test.cpp',

src/tests/compiler_tests/ShaderValidation_test.cpp

@@ -3268,4 +3268,20 @@ TEST_F(FragmentShaderValidationTest, BuiltinESSL31FunctionDeclaredInESSL30Shader
     {
         FAIL() << "Shader compilation failed, expecting success:\n" << mInfoLog;
     }
-}
\ No newline at end of file
+}
+
+// Attempting to declare num_views without enabling OVR_multiview.
+TEST_F(VertexShaderValidationTest, InvalidNumViews)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "layout (num_views = 2) in;\n"
+        "void main() {\n"
+        "}\n";
+
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure:\n" << mInfoLog;
+    }
+}

src/tests/test_utils/compiler_test.cpp

@@ -17,34 +17,6 @@ namespace sh
 namespace
 {
 
-class ShaderVariableFinder : public TIntermTraverser
-{
-  public:
-    ShaderVariableFinder(const TString &variableName, TBasicType basicType)
-        : TIntermTraverser(true, false, false),
-          mVariableName(variableName),
-          mNodeFound(nullptr),
-          mBasicType(basicType)
-    {
-    }
-
-    void visitSymbol(TIntermSymbol *node)
-    {
-        if (node->getBasicType() == mBasicType && node->getSymbol() == mVariableName)
-        {
-            mNodeFound = node;
-        }
-    }
-
-    bool isFound() const { return mNodeFound != nullptr; }
-    const TIntermSymbol *getNode() const { return mNodeFound; }
-
-  private:
-    TString mVariableName;
-    TIntermSymbol *mNodeFound;
-    TBasicType mBasicType;
-};
-
 class FunctionCallFinder : public TIntermTraverser
 {
   public:
@@ -237,15 +209,6 @@ bool MatchOutputCodeTest::notFoundInCode(const char *stringToFind) const
     return true;
 }
 
-const TIntermSymbol *FindSymbolNode(TIntermNode *root,
-                                    const TString &symbolName,
-                                    TBasicType basicType)
-{
-    ShaderVariableFinder finder(symbolName, basicType);
-    root->traverse(&finder);
-    return finder.getNode();
-}
-
 const TIntermAggregate *FindFunctionCallNode(TIntermNode *root, const TString &functionName)
 {
     FunctionCallFinder finder(functionName);

src/tests/test_utils/compiler_test.h

@@ -16,6 +16,7 @@
 #include "angle_gl.h"
 #include "compiler/translator/TranslatorESSL.h"
 #include "GLSLANG/ShaderLang.h"
+#include "compiler/translator/FindSymbolNode.h"
 
 namespace sh
 {
@@ -92,10 +93,6 @@ class MatchOutputCodeTest : public testing::Test
     std::map<ShShaderOutput, std::string> mOutputCode;
 };
 
-const TIntermSymbol *FindSymbolNode(TIntermNode *root,
-                                    const TString &symbolName,
-                                    TBasicType basicType);
-
 // Returns a pointer to a function call node with a mangled name functionName.
 const TIntermAggregate *FindFunctionCallNode(TIntermNode *root, const TString &functionName);
 }